Clamp for blade for higher rating dyna-mate caps

ABSTRACT

A conductor clamp is provided capable of rapid assembly and reliable securing of a conductor to a power blade, contact or the like. Rapid assembly is achieved by forming a U-shaped conductor troth, inserting a winged contact into the U and rotating the winged contact to bring the wings into engagement with conforming slots in the uprights of the U. A screw threaded through the winged contact prevents disassembly.

United States Patent 1191 Sheldon 1451 July 17, 1973 CLAMP FOR BLADE FORHIGHER RATING 1 DYNA-MATE CAPS [75] Inventor: Luther M. Sheldon,Cranston, R.I.

[73] Assignee: General Electric Company,

Providence, R.I.

[22] Filed: June 24, 1971 [21] Appl. No.: 156,179

[52] US. Cl. .J 339/272 VC [51] Int. Cl. H01r 11/10 [58] Field of Search339/263, 272

[56] References Cited UNITED STATES PATENTS 2,782,388 2/1957 Opalcnik etal..... 339/272 UC 2,967,290 l/l96l Zellei' 339/272 R FOREIGN PATENTS ORAPPLICATIONS l,045,330 l0/ 1966 Great Britain 339/272 UC 12/1923 Germany.1 339/272 R 2/1952 Germany 339/272 UC Primary Examiner-Joseph M.McGlynn Attorney-Paul E. Rochford et al.

[57] ABSTRACT A conductor clamp is provided capable of rapid assemblyand reliable securing of a conductor to a power blade, contact or thelike. Rapid assembly is achieved by forming a U-shaped conductor troth,inserting a winged contact into the U and rotating the winged contact tobring the wings into engagement with conforming slots in the uprights ofthe U. A screw threaded through the winged contact preventsdisassembly..

1 Claim, 7 Drawing Figures This invention relates to wire clamps andmore particularly wire clamps formed as part of contacts or blades orthe like of wiring devices.

In many wiring devices power blades or contacts of female connectors toreceive power blades must be attached to power supply conductors,eithersingle solid strand or multistrand. For higher power ratings effectiveclamping of some portion of a contact or blade to the conductor isneeded to avoid problems of loss of effective contact due to looseningof the clamping hold on the power conductor, or due to expansion andcontraction of the clamp and conductor due to the heavy power conductedin the device or to heating at the clamp due to poor contact. Thislatter problem is particularly troublesome in use of aluminum conductorsbecause of the strong'tendency of aluminum metal to change itsdimensions under stress and because of its tendency to build up anon-conductive surface oxide layer as a result of heating. As the layerbuilds up greater heating results and this leads to further oxideproduction. Reliable gripping of a conductor and particularly analuminum conductor is important for this reason.

Patents which teach various forms of cable clamps to serve the purposeof connecting cables to various forms of connector and which illustratethe state of this art include the following: US. Pat. Nos. 2,958,068;2,602,104; 3,133,781; 2,516,572; 2,780,793; 2,786,190; 2,877,443;2,938,191; 2,164,021; and 3,041,576.

Further direct contact of the conductor with the element to receive theelectric power is important as metal joints made by soldering, braizingor welding can be faulty and flaws may not be apparent. Transmissionofhigh power through faulty joints can cause breakdown and damage.

It is accordingly an object of the present invention to provide a lowcost reliable connector suitable for use in connection with receivingrelatively high power electric supply from solid or stranded conductors.

Another object is to provide a clamp effective in receiving high currentflows of 30 or 50 amps from conductors into electrical blades andcontacts of caps and connectors.

Still another object is to facilitate rapid reliable mounting ofelectrical parts to conductors.

A further object is to provide a clamp for a cable usable with copper oraluminum conductors.

Still a further object is to provide a clamp capable of quick assemblyand disassembly from a cable.

Other objects and advantages of the present invention will be in partapparent and in part pointed out in the description which follows.

In one of its broader aspects the objects of the invention may beachieved by providing a clamp for removably securing a power conductorof heavy cross-section in electrical engagement with a metal connectorelement comprising,

a semi-rigid U-shaped element having a long closed end slot in oneupright thereof and a shorter closed-end slot in the other uprightthereof,

a semi-rigid cross piece for said U-shaped element,

said cross piece having oppositely extending short wings adapted to fitinto the slots of'said U-shaped element on rotation of said cross piecewithin the hollow of the U a threaded opening in the winged portion ofsaid cross piece,

a pressure screw in said opening,

said cross piece having a portion extending from said winged portionserving as an electrical contact to transmit electric power receivedfrom a conductor clamped between the pressure screw and the well of saidU- shaped member.

In the description which follows the manner of carrying out theinvention will be made clearer by reference to the accompanying drawingsin which:

FIG. 1 is a perspective view of the assembled combination conductorclamp and blade contact showing an exposed end of an insulated conductorpoised for entry into the clamp.

FIG. 2 is a similar view of the clamp and contact element of FIG. 1after disassembly of the elements.

FIG. 3 is an end elevation view of the clamp portion of the device ofFIG. 1.

FIG. 4 is a side elevation of one side of the clamp and contact as shownin FIG. 1.

FIG. 5 is a side elevation of the opposite side of the clamp and contactas shown in FIG. 1.

FIG. 6 is a vertical section of the clamp taken along the lines 6--6 ofFIG. 4.

FIG. 7 is a top plan view of the clamp and portion of the contact asillustrated in FIG. 1.

Referring first to FIG. 1 a sheathed wire 10 having a stripped end 12 isshown in position to be inserted into the combination wire clamp andcontact of this invention. The wire itself may be solid or it may bestranted, it may be copper or aluminum or other metal such as coppersheathed aluminum.

The wire clamp is made up of three pieces a semirigid U-shaped wirereceiving trough 14, a semi-rigid cross member 16 having a contactformed integrally therewith, and a pressure screw 18.

The construction and operation of the clamp will be made clear byreference to the other FIGS. 2 through 7 in the description whichfollows.

The U element 14 is formed of a metal such as brass of a gaugesufficient to withstand deformation as the clamping pressure isdeveloped on an inserted conductor by turning down screw 18. Asemi-rigid structure results from use of strip of sufficient gauge informing the U.

A slot is formed in each upright of the U. One slot 20 is deep andpermits rotation of a winged cross piece 24 to bring the short wing 26into engagement with the top surface defining deep slot 20.

The second slot 22 is shallower than its opposite counterpart, slot 20,but its upper edge is parallel with the upper edge of slot 20. In thisway a cross member such as 16 is held generally horizontal when the U isoriented generally vertically.

A second short wing 28 extends from cross member 24 in a directionopposite to the wing 26. The wing 28 is of a dimension to enter into andbe held within slot 22 In assembling the cross member into the U thecross member is first rotated to approximately the position shown inFIG. 2 relative to the U and the slots of the U. In the rotated positionshown it enters the hollow of the U between the uprights thereof andcomes freely into place with its wings proximate the slots.

The cross piece is then counter rotated so that wing 28 enters shallowslot 22 directly by turning and sliding in. By contrast wing 26 rotatesup through the depth of the deeper slot 20 until its upper surface abutsthe top surface of slot 20.

A pressure screw 18 is then screwed into the threaded hole 19 and whenin position prevents the rotation of the cross piece 24 to a degreewhich permits its removal from the U.

The structure is unique in the simplicity and facility of the assemblyof the cooperating parts where the cross member part is itself a part ofa contact supplying or receiving a high level of power from anothercontact.

Thus the structure which results is not the equivalent of a contact inwhich two shallow slots are formed in a U and a narrow cross piece isslid into the slots from one external side as in this case no extendingcontact element such as 15 of FIG. 1 would be present as an integralpart of the cross piece.

Rapid reliable facile assembly of a clamp and contact combined structureis a feature of the structure of the present invention.

Substantial pressure can be developed on a solid orstranded wire roughlyin the range of No. to No. 4 wire for the same size clamp in the formshown in the FIGURES and satisfactory transfer through the contact andclamp of high electric power loads is feasible without over heating ordamage to the structure or enclosure in which it is contained. Thestructure easily handles 60 ampere AC or DC loads at 250 volts with lessthan 30 rise above ambient temperature.

An important point in the construction of the present invention is thatblade configurations for various locking, angled, grounding or similarassemblies can be and have been constructed using the same clamp astaught herein.

This clamp is effective in use partly because the combination of theshort and long slot keeps the cross piece in its upper position so thatthe trough is open to receive a cable end and the pressure screw servesas a counter rotation stop for the cross piece.

What is claimed is:

1. An electrical connector for removably securing a power conductor ofheavy cross-section in electrical engagement with a metal contact bladecomprising,

a semi-rigid U-shaped element, said element having an open central well,having a closed end slot extending along a substantial length of oneupright thereof, and having a shorter closed end slot in the otherupright thereof,

a semi-rigid cross piece, said cross piece having oppositely extendingshort wings, said short wings having widths matching the widths of theslots of said U-shaped element and lengths approximately matching thatof the thickness of the uprights of said U-shaped element,

a threaded opening generally centrally of the winged portion of saidcross piece,

a pressure screw within said opening said cross piece having a portionthereof extending from said winged portion to serve as an electricalcontact to transmit power received from a conductor clamped between thepressure screw and the well of the U-shaped member.

1. An electrical connector for removably securing a power conductor ofheavy cross-section in electrical engagement with a metal contact bladecomprising, a semi-rigid U-shaped element, said element having an opencentral well, having a closed end slot extending along a substantiallength of one upright thereof, and having a shorter closed end slot inthe other upright thereof, a semi-rigid cross piece, said cross piecehaving oppositely extending short wings, said short wings having widthsmatching the widths of the slots of said U-shaped element and lengthsapproximately matching that of the thickness of the uprights of saidU-shaped element, a threaded opening generally centrally of the wingedportion of said cross piece, a pressure screw within said opening saidcross piece having a portion thereof extending from said winged portionto serve as an electrical contact to transmit power received from aconductor clamped between the pressure screw and the well of theU-shaped member.